Disk device with stopper for movable member

ABSTRACT

According to one embodiment, a stopper of a disk device, to regulate movement of movable member of a disk device, includes a fixing member to be fixed to a supporter of the disk device, and a cushioning member formed of a rubber and attached to the fixing member. The cushioning member includes a contact surface which contacts the fixing member, a first contact surface which can contact the supporter of the disk device, and a second contact surface which can contact a movable member in the disk device, the first contact surface has a first surface adhesive force based on adhesion of the rubber, and the second contact surface is subjected to a non-adhesive surface treatment and has a second surface adhesive force which is less than the first surface adhesive force.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 15/460,581,filed Mar. 16, 2017 and is based upon and claims the benefit of U.S.Provisional Application No. 62/430,686, filed Dec. 6, 2016, the entirecontents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a stopper used for adisk device, and a disk device comprising the stopper.

BACKGROUND

A magnetic disk drive which functions as a disk device comprises ahousing which includes a base and a top cover, and the housingaccommodates a rotatable magnetic disk and a rotatable head actuatorwhich supports a magnetic head. The housing further accommodates astopper which stops the head actuator, which is a movable member, at apredetermined rotation position, or a stopper which regulates a range ofmovement of another movable member.

To reduce the collision impact of the head actuator or the other movablemember on the stopper, the stopper comprises a cushioning member(stopper rubber) which is made of a rubbery elastic material or thelike. As the material of the cushioning member, in light of impactattachment characteristics, fluorine rubber is often used. However,fluorine rubber is highly adhesive, and if the head actuator is left incontact with the cushioning member for a long time, the head actuatorwill be fixed to the cushioning member. In that case, the head actuatorwill not move next time when the disk device is activated.

To prevent such fixation, a method of providing a plurality ofprojections on the outer surface of the cushioning member and reducingthe contact surface of the cushioning member with respect to the headactuator, a method of providing a fixation prevention film on thesurface of the cushioning member, and the like have been proposed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an external appearance of a hard diskdrive (HDD) of a first embodiment.

FIG. 2 is an exploded perspective view of a carriage and a voice coilmotor (VCM) of the HDD.

FIG. 3 is a plan view of the carriage and the VCM of the HDD in a statewhere one yoke is removed from the HDD.

FIG. 4 is a perspective view of an external appearance of an outerstopper.

FIG. 5 is an exploded perspective view of the outer stopper.

FIG. 6 is a sectional view of the outer stopper which is attached to ahousing.

FIG. 7 is a flowchart showing a manufacturing process of the stopper.

FIG. 8 is a schematic diagram showing an example of a cutting process.

DETAILED DESCRIPTION

Various Embodiments will be described hereinafter with reference to theaccompanying drawings. In general, according to one embodiment, astopper of a disk device comprises: a fixing member which is to be fixedto a supporter of the disk device; and a cushioning member formed of afluorine rubber and attached to the fixing member. The cushioning membercomprises a contact surface which contacts the fixing member, a firstcontact surface which can contact the supporter of the disk device, anda second contact surface which can contact a movable member in the diskdevice, the first contact surface has a first surface adhesive forcebased on adhesion of the fluorine rubber, and the second contact surfaceis subjected to a non-adhesive surface treatment and has a secondsurface adhesive force which is less than or equal to 1/20 the firstsurface adhesive force.

As the disk device, a hard disk drive (HDD) of an embodiment will bedescribed.

FIG. 1 is an exploded perspective view of the internal structure of theHDD of the embodiment, and FIG. 2 is an exploded perspective view of acarriage and a VCM of the HDD.

As shown in FIG. 1, the HDD comprises a flat andsubstantially-rectangular housing 10. The housing 10 includes a base 12which is formed in the shape of a rectangular box and has an open uppersurface, and a top cover 14 which is secured to the base 12 by aplurality of screws and closes the upper end opening of the base 12. Thebase 12 includes a rectangular bottom wall 12 a which is spaced apartfrom the top cover 14 and is opposed to the top cover 14, and a sidewall 12 b which stands along the periphery of the bottom wall 12 a, andfor example, the base 12 is aluminum and is integrally formed. The topcover 14 is, for example, a SUS plate which is pressed into arectangular plate which has substantially same dimensions as those ofthe bottom wall 12 a of the base 12. A frame-shaped gasket (packing orseal) 16 is provided along the periphery of the inner surface of the topcover 14. When the top cover 14 is attached to the base 12, the gasket16 is held between the upper surface of the side wall 12 b and the topcover 14 and keeps the inside of the housing 10 airtight. Further, aring-shaped cushion 17 and a disk-shaped packing 18 are provided on theinner surface of the top cover 14. When the top cover 14 is attached tothe base 12, the cushion 17 will contact one yoke of a VCM, which willbe described later, and the packing 18 will contact one end of astopper, which will be described later.

The housing 10 accommodates a plurality of magnetic disks 20 asdisk-shaped recording media, and a spindle motor 22 as a drive sectionwhich supports and rotates the magnetic disks 20. The spindle motor 22is provided on the bottom wall 12 a. Each of the magnetic disks 20 has adiameter of, for example, 88.9 mm (3.5 inches) and has a magneticrecording layer on the upper surface or the lower surface. The magneticdisks 20 are coaxially engaged with a hub (not shown) of the spindlemotor 22, are clamped by a clamp spring 23, and are fixed to the hub. Inthis way, the magnetic disks 20 are supported in parallel to the bottomwall 12 a of the base 12. The magnetic disks 20 are rotated at apredetermined rotation rate by the spindle motor 22.

Note that, although the number of the magnetic disks 20 accommodated inthe housing 10 is assumed to be, for example, five in the presentembodiment as shown in FIG. 1, the number of the magnetic disks 20 isnot limited to five. Further, a single magnetic disk 20 may beaccommodated in the housing 10.

The housing 10 further accommodates a plurality of magnetic heads 24which record or reproduce information on or from the magnetic disks 20,and a head actuator 26 which movably supports these magnetic heads 24with respect to the magnetic disks 20. The head actuator 26 comprises acarriage 28 which is rotatably provided on the base 12 and supports themagnetic heads 24, and a voice coil motor (hereinafter referred to as aVCM) 30 which rotates and positions the carriage 28. Further, thehousing 10 also accommodates a ramp load mechanism 32 which holds themagnetic heads 24 in an unload position which is away from the magneticdisks 20 when the magnetic heads 24 move to the outermost circumferenceof the magnetic disks 20, and a substrate unit 34 on which electroniccomponents such as a conversion connector are mounted. The substrateunit 34 is formed of a flexible printed circuit (FPC) board, and the FPCboard is electrically connected to the magnetic heads 24 and the voicecoil of the VCM 30 via a junction FPC board on the carriage 28.

As shown in FIGS. 1 and 2, the carriage 28, which functions as a movablemember in the present embodiment, comprises a bearing unit 36 which isrotatably provided on the base wall 12 a of the base 12, a plurality ofarms 38 which extend from the bearing unit 36, and a plurality ofsuspensions 40 which extend from the respective arms 38, and themagnetic heads 24 are supported at the distal ends of the suspensions40, respectively. Here, such a structure where the sleeve of the bearingunit 36 is integrally formed with the arms 38, that is, the so-called Eblock may also be adopted. The carriage 28 comprises a support frame 42which extends from the bearing unit 36 in the opposite direction withrespect to the arms 38. A voice coil 44, which constitutes a part of theVCM 30, is supported by the support frame 42. The VCM 30 includes a pairof yokes 45 a and 45 b which is provided on the bottom wall 12 a of thebase 12, and a magnet 46 which is fixed to at least one of these yokes.

FIG. 3 is a plan view of the carriage and the VCM of the HDD in a statewhere one yoke is removed from the HDD.

As shown in FIGS. 1 to 3, the yoke 45 a of the VCM 30 is mounted on andfixed to the bottom wall 12 a of the base 12. The other yoke 45 b isspaced apart and is opposed to the one yoke 45 a. The voice coil 44 ofthe VCM 30 is interposed between the pair of yokes 45 a and 45 b and isopposed to the magnet 46. When a current is applied to the voice coil44, a magnetic field is produced. Further, as the magnetic filedinteracts with the magnetic field of the magnet 46, the carriage 28 isrotated.

In the housing 10, an outer stopper 50 and an inner stopper 60 whichregulate the rotation range of the carriage 28 are provided. The outerstopper 50 stands on the bottom wall 12 a of the base 12 which functionsas a supporter, and is arranged near the magnetic disks 20 and the yoke45 a. As shown by solid lines in FIG. 3, when the carriage 28 rotatesclockwise from the outer circumference of the magnetic disks 20 up tosuch a position where the magnetic heads 24 are mounted on the ramp ofthe ramp load mechanism, the support frame 42 of the carriage 28contacts the outer stopper 50. In this way, the outer stopper 50restricts further rotation of the carriage 28 and defines the outwardmovement limit of the carriage 28 and the magnetic heads 24.

According to the present embodiment, the inner stopper 60 stands betweenthe yokes 45 a and 45 b which function as supporters, and is arranged onthe opposite side of the carriage 28 with respect to the outer stopper50. As shown by double-dot-dash lines in FIG. 3, when the carriage 28rotates counterclockwise up to such a position near the innercircumference of the magnetic disks 20, the support frame 42 of thecarriage 28 contacts the inner stopper 60. In this way, the innerstopper 60 restricts further rotation of the carriage 28 and defines theinner movement limit of the carriage 28 and the magnetic heads 24.

Next, the structure of the outer stopper 50 will be described in detail.FIG. 4 is a perspective view of the external appearance of the outerstopper, FIG. 5 is an exploded perspective view of the outer stopper,and FIG. 6 is a sectional view of the outer stopper which is attached tothe housing 10.

As shown in FIGS. 4 and 5, the outer stopper 50 includes a support shaft(stopper pin) 52 as a metal fixing member, and a cushioning memberprovided around the support shaft 52, for example, a stopper rubber 54.The support shaft 52 comprises integrally a first end 52 a which islocated at one end in the axial direction, a second end 52 b which islocated at the other end in the axial direction, and an annular flange52 c which is provided near the second end 52 b. The diameter of thefirst end 52 a is greater than the diameter of the other part of thesupport shaft 52. As will be described later, the first end 52 a isengaged with or fixed to the bottom wall 12 a of the base 12, and thesupport shaft 52 perpendicularly stands with respect to the bottom wall12 a.

The cushioning member is selected from rubbery elastic materials(adhesive materials) whose outgassing characteristics are low enough tohave no impact on the function of the HDD and whose hardness is 50 to 80Hs (JIS-A) such that the cushioning member has predetermined cushioningcharacteristics, and rubber such as fluorine rubber or butyl rubber orelastomer such as polyurethane elastomer can be used as the material ofthe cushioning member. In the present embodiment, the stopper rubber 54is highly-adhesive fluorine rubber and in formed in the shape of acylinder, for example, a circular cylinder. The stopper rubber 54includes an inner hole 56 which coaxially penetrates through the stopperrubber 54. The support shaft 52 is inserted into the inner hole 56, andthe stopper rubber 54 is fitted around the support shaft 52 between thefirst end 52 a and the flange 52 c.

The stopper rubber 54 includes an inner periphery 58 a which defines theinner hole 56, an outer periphery 58 b which can contact the carriage28, a first end surface 58 c which is adjacent to the first end 52 a ofthe support shaft 52, and a second end surface 58 d which is adjacent tothe flange 52 c. The inner periphery 58 a constitutes a contact surfacewhich is in contact with the surface of the support shaft 52, the firstend surface 58 c constitutes a first contact surface (seating surface)which can contact the bottom wall 12 a of the base 12, and the outerperiphery 58 b constitutes a second contact surface which can contactthe carriage 28.

The stopper rubber 54 is partly subjected to a non-adhesive surfacetreatment. In the present embodiment, the non-adhesive surface treatmentis applied only to the outer periphery (second contact surface) 58 b ofthe stopper rubber 54. The inner periphery 58 a, the first end surface(first contact surface) 58 c, and the second end surface 58 d are notsubjected to the non-adhesive surface treatment and have a first surfaceadhesive force based on the adhesion of fluorine rubber. The outerperiphery 58 b is subjected to the non-adhesive surface treatment andhas a second surface adhesive force which is significantly less than thefirst surface adhesive force and is, for example, 1/200 to 1/10 thefirst surface adhesive force, more preferably, less than or equal to1/20 the first surface adhesive force. In the non-adhesive surfacetreatment, for example, the outer periphery 58 b of the stopper rubber54 is immersed in a solution which accelerates a cross-linking reactionof fluorine rubber, and in this way, the adhesion and the surfaceadhesive force of the outer periphery 58 b is reduced.

For example, the first surface adhesive force of the surfaces (the innerperiphery 58 a, the first end 58 c, and the second end 58 d) which arenot subjected to the non-adhesive surface treatment was measured underthe following conditions. That is, after a contacting object was leftfor a predetermined time in a state where the contact object was pressedagainst the rubber surface under a predetermined application load, thecontacting object was removed from the rubber surface, and at this time,the required force (surface adhesive force) was measured.

More specifically, under the following conditions: the material of thecontacting object: aluminum, the contact portion: the first end surface(seating surface) of the rubber, the surface roughness Rz: 12.5 μm orless, the application load: 2N, the area of the seating surface of therubber: 11 mm², the temperature and the humidity at which the contactingobject was left: the contacting object was left at 80° C. and 80% RH forone week and was then left at room temperature (25±10° C. and 55±20% RH)for two hours, and the temperature and the humidity at the time ofmeasurement: 25±10° C. and 55±20% RH, the first surface adhesive forcewas 3N or more.

For example, the second surface adhesive force of the outer periphery(the second contact surface) 58 b which is subjected to the non-adhesivesurface treatment was measured under the following conditions. That is,after a contacting object was left for a predetermined time in a statewhere the contact object was pressed against the rubber surface under apredetermined application load, the contacting object was removed fromthe rubber surface, and at this time, the required force (surfaceadhesive force) was measured.

More specifically, under the following conditions: the material of thecontacting object: aluminum, the contact portion: the outer periphery ofthe rubber, the surface roughness Rz: 3.2 μm or less, the applicationload: 1.5N, the contact width: 3 mm, the temperature and the humidity atwhich the contacting object was left: the contacting object was left at80° C. and 80% RH for ten hours and was then left at room temperature(25±10° C. and 55±20% RH) for two hours, and the temperature and thehumidity at the time of measurement: 25±10° C. and 55±20% RH, the secondsurface adhesive force was 0.015N or less.

As is evident from the above, the inner periphery 58 a, the first endsurface 58 c and the second end surface 58 d of the stopper rubber 54which are not subjected to the non-adhesive surface treatment have thefirst surface adhesive force of 3N or more based on the adhesion offluorine rubber itself. On the other hand, the outer periphery (thesecond contact surface) 58 b of the stopper rubber 54 is subjected tothe non-adhesive surface treatment, and the second surface adhesiveforce is 0.015N or less, that is, the second surface adhesive force issignificantly small and is equal to or less than 1/20, for example,1/213 the first surface adhesive force. It would be sufficient if thesecond surface adhesive force is not great enough to permanently attachto the carriage 28. Thus, the second surface adhesive force isappropriately adjustable.

As the support shaft 52 is inserted into the inner hole 56, the stopperrubber 54 of the above-described structure is provided around thesupport shaft 52. The inner periphery 58 a of the stopper rubber 54 ispressed against the periphery of the support shaft 52 by the elasticityof the stopper rubber 54 and is in contact with the outer periphery ofthe support shaft 52. Further, due to the adhesion of fluorine rubber,the inner periphery 58 a is adherent or attached to the outer peripheryof the support shaft 52. Therefore, the stopper rubber 54 is notrotatable with respect to the support shaft 52 but is fixed to thesupport shaft 52.

As shown in FIG. 6, as the first end 52 a of the support shaft 52 isengaged with an engagement hole 62 which is formed in the bottom wall 12a of the base 12, the outer stopper 50 is fixed to the bottom wall 12 aand perpendicularly stands with respect to the bottom wall 12 a.Further, the second end 52 b of the support shaft 52 is in contact withthe packing 18 which is provided on the top cover 14. The support shaft52 is pushed toward the bottom wall 12 a by the elasticity of thepacking 18. The stopper rubber 54 is pushed toward the bottom wall 12 aby the flange 52 c of the support shaft 52. The first end surface(seating surface) 58 c of the stopper rubber 54 is pressed against thebottom wall 12 a and is attached to the bottom wall 12 a around theengagement hole 62. In this way, the stopper rubber 54 seals theengagement hole 62 of the bottom wall 12 a airtight.

When the carriage 28 rotates toward the outer circumference of themagnetic disks 20 and approaches to the outward movement limit, thesupport frame 42 of the carriage 28 collides against the outer periphery58 b of the stopper rubber 54 and stops. At this time, the stopperrubber 54 reduces or absorbs the collision impact from the support frame42 and stops the carriage 28 at the predetermined position. The outerperiphery 58 b of the stopper rubber 54 which contacts the support frame42 is subjected to the non-adhesive surface treatment and has thesignificantly-small second surface adhesive force. Therefore, even ifthe support frame 42 is in contact with the outer periphery 58 b for along time, the support frame 42 will not be attached or adhered to thestopper rubber 54.

Note that the inner stopper 60 includes the support shaft 52 and thestopper rubber 54 and has the same structure as that of the outerstopper 50. The inner stopper 60 stands on the yoke 45 a which isprovided on the base 12 side, and the upper end of the support shaft isengaged or in contact with the yoke 45 b. In this way, the inner stopper60 is arranged between the pair of yokes 45 a and the 45 b, and theouter periphery of the stopper rubber constitutes the second contactsurface which can contact the support frame 42 of the carriage 28. Thatis, when the carriage 28 rotates toward the inner periphery of themagnetic disks 20 and approaches the inward movement limit, the supportframe 42 of the carriage 28 collides against the outer periphery of theinner stopper 60 and stops. At this time, the stopper rubber reduces orabsorbs the collision impact from the support frame 42 and stops thecarriage 28 at the predetermined position. The outer periphery 58 b ofthe stopper rubber which contracts the support frame 42 is subjected tothe non-adhesive surface treatment and has the significantly-smallsecond surface adhesive force. Therefore, even if the support frame 42is in contact with the inner stopper 60 for a long time, the supportframe 42 will not be attached to the inner stopper 60.

Next, an example of a method of manufacturing the stopper will bedescribed. FIG. 7 is a flowchart showing the manufacturing process. Asshown in FIG. 7, firstly, a long thin fluorine rubber tube is prepared,and the rubber tube is washed (ST1). A dummy shaft is inserted into theinner hole of the rubber tube, and the rubber tube is firmly attached tothe dummy shaft (ST2). Then, the rubber tube is immersed in a treatmentsolution for a predetermined time, and a non-adhesive surface treatmentis applied to the outer periphery of the rubber tube (ST3). After therubber tube is removed from the treatment solution, the rubber tube isapplied to a heat treatment at about 200° C. for one day, and the outerperiphery of the rubber tube is cured (cross-linked) (ST4).

Subsequently, the dummy shaft is removed from the rubber tube (ST5), therubber tube is cut into predetermined lengths, and stopper rubbers areformed (ST6). A support shaft is inserted into the inner hole of thestopper rubber, and the stopper rubber is fixed to the support shaft(ST7). Finally, the whole stopper is washed (ST8), and the stopper iscompleted.

Note that, when the rubber tube is cut into the stopper rubbers, thesections constitute the first end surface 58 c and the second endsurface 58 d of the stopper rubber 54. It is preferable that the firstend surface 58 c and the second end surface 58 d, in particular, thefirst end surface (seating surface) 58 c should have a small flatnesstolerance value such that the first end surface 58 c will be in closecontact with the supporter of the HDD, in this case, the base bottomwall 12 a.

Therefore, in the process of cutting the rubber tube, as shown in FIG.8, while a dummy shaft 82 is inserted in a rubber tube 80, the rubbertube 80 may be rotated about a central axis C of the dummy shaft 82, andthe rubber tube 80 may be cut in by a cutter 84 from the outer peripheryof the rubber tube 80 toward the dummy shaft 82. In this case, torelease the cutting edge of the cutter 84, notches or grooves 83 may beformed in the outer periphery of the dummy shaft 82 in positionscorresponding to cutting positions of the rubber tube 80.

According to the above-described cutting method, since the rubber tube80 will not be squashed when the rubber tube 80 is cut into the stopperrubbers, a section having a small flatness tolerance value, that is, thefirst end surface 58 c can be formed. It is preferable that the flatnesstolerance value of the first end surface 58 c should be less than theamount of compression of the stopper rubber 54 which is derived fromparameters such as the gutter between the support shaft 52 and theengagement hole 62 of the bottom wall 12 a, the length of the supportshaft, the hardness of the stopper rubber 54, the hardness of the coverpacking 18, and the amount of pressure of the stopper rubber.

According to the HDD of the above-described structure of the presentembodiment, in each of the outer stopper 50 and the inner stopper 60,only the second contact surface (outer periphery 58 b), which cancontact the movable member, of the stopper rubber 54 is subjected to thenon-adhesive surface treatment, and the second surface adhesive force ofthe second contact surface is significantly reduced. Therefore, it ispossible to prevent adhesion of the carriage 28 to these stoppers 50 and60 and to ensure smooth operation of the carriage 28 for a long time.Further, since there is no need to attach any additional member such asan adhesion prevention film or the like to the stopper, the componentsof the stopper can be reduced, and the manufacturing cost can bereduced, accordingly.

The inner periphery 58 a, the first end surface 58 c and the second endsurface 58 d of the stopper rubber 54 are not subjected to thenon-adhesive surface treatment and have the great first surface adhesiveforce based on the adhesion of fluorine rubber. Therefore, the first endsurface (seating surface) 58 c of the stopper rubber 54 is tightly andfirmly adhered to the surface (upper surface) of the bottom wall 12 a bythe first surface adhesive force. In this way, the stopper rubber 54seals the engagement hole 62 of the bottom wall 12 a airtight.Consequently, even if the carriage 28 collides with the stopper rubber54 at high speed, a gap will not be formed between the first end surface58 c and the bottom wall 12 a, and thus dusts in the engagement hole 62,cutting scraps (contaminations) of aluminum (the base) and the like willdefinitely be prevented from scattering over the housing 10. Further, asthe flatness tolerance value of the first end surface 58 c is reduced,it is possible to make the adhesion of the first end surface 58 c to thebase wall 12 a even across the entire first end surface 58 c. Therefore,the first end surface 58 c can be more firmly attached to the bottomwall 12 a.

Still further, the inner periphery 58 a of the stopper rubber 54 isfirmly attached to the periphery of the support shaft 52. Therefore,when the carriage 28 collides with the stopper rubber 54 at high speedand even if torque acts on the stopper rubber 54 in the direction ofrotating the stopper rubber 54, the stopper rubber 54 will not rotatearound the support shaft 52 but will remain fixed. Therefore,contaminations associated with the rotation of the stopper rubber 54with respect to the support shaft 52 will not be produced, orcontaminations associated with the rotation of the stopper rubber withrespect to the bottom wall will not be produced or scatter over.

Note that the inner stopper 60 can achieve the same technical effect asthat of the outer stopper.

From the above, according to the present embodiment, it is possible toreliably prevent attachment of a movable member and scattering ofcontaminations, to realize a stopper which can be inexpensivelymanufactured, and to realize a magnetic disk drive comprising thestopper.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

For example, although the non-adhesive surface treatment is applied tothe entire outer periphery of the stopper rubber in the presentembodiment, this is in no way restrictive, and the non-adhesive surfacetreatment may be applied only to the contact area of the outer peripherywhich can contact the movable member. Further, the shape of the stopperrubber is not limited to a circular cylinder but may be selected fromvarious other shapes. Still further, the movable member which contactsthe stopper is not limited to the carriage but may be various othermovable members. In the disk drive, the number of the magnetic disks andthe number of the magnetic heads can be appropriately increased orreduced as needed, and the magnetic disk can be formed in various othersizes.

What is claimed is:
 1. A stopper which regulates movement of a movablemember of a disk device, the stopper comprising: a fixing member whichis to be fixed to a supporter of the disk device; and a cushioningmember which is formed of a rubber and is attached to the fixing member,wherein the cushioning member includes a contact surface which contactsthe fixing member, a first contact surface which is configured tocontact the supporter of the disk device, and a second contact surfacewhich is configured to contact the movable member, the first contactsurface has a first surface adhesive force of the rubber, and the secondcontact surface has a second surface adhesive force which is less thanthe first surface adhesive force.
 2. The stopper of claim 1, wherein thefixing member includes a support shaft which comprises a first end whichengages with the supporter of the disk device, and the cushioning memberis formed in a shape of a cylinder with an inner hole into which thesupport shaft is inserted, and comprises an outer periphery whichconstitutes the second contact surface and an inner periphery whichconstitutes the contact surface and defines the inner hole.
 3. Thestopper of claim 2, wherein the inner periphery of the cushioning memberhas the first surface adhesive force based on the adhesion of the rubberand is attached to the support shaft.
 4. The stopper of claim 2, whereinthe first contact surface of the cushioning member is located near thefirst end of the support shaft and is configured to contact thesupporter of the disk device.
 5. The stopper of claim 4, wherein thefirst contact surface has a flatness tolerance value which is less thanan amount of compression of the cushioning member which is derived fromparameters including hardness of the rubber.
 6. The stopper of claim 1,wherein the second contact surface is subjected to a non-adhesivesurface treatment and the second surface adhesive force is less than orequal to 1/20 the first surface adhesive force.
 7. A disk devicecomprising: a base; a rotatable disk recording medium in the base; ahead which writes information to the recording medium; a rotatablecarriage which supports the head; and a stopper which is configured tocontact the carriage, wherein the stopper comprises: a fixing memberwhich is fixed to a supporter of the disk device; and a cushioningmember formed of an adhesive material and attached to the fixing member,wherein the cushioning member comprises a contact surface which contactsthe fixing member, a first contact surface which contacts the supporter,and a second contact surface which is configured to contact thecarriage, the first contact surface has a first surface adhesive forcebased on adhesion of the adhesive material, and the second contactsurface has a second surface adhesive force which is less than or equalto the first surface adhesive force.
 8. The disk device of claim 7,wherein the fixing member includes a support shaft which comprises afirst end which engages with the supporter, and the cushioning member isformed in a shape of a cylinder with an inner hole into which thesupport shaft is inserted, and comprises an outer periphery whichconstitutes the second contact surface and an inner periphery whichconstitutes the contact surface and defines the inner hole.
 9. The diskdevice of claim 8, wherein the first contact surface of the cushioningmember is located near the first end of the support shaft and isconfigured to contact a surface of the supporter.
 10. The disk device ofclaim 8, wherein the inner periphery of the cushioning member has thefirst surface adhesive force based on the adhesion of the adhesivematerial and is adhered to the support shaft.
 11. The disk device ofclaim 8, wherein the supporter includes an engagement hole, and thefirst end of the support shaft engages with the engagement hole, and thefirst contact surface of the cushioning member is adhered to thesupporter around the engagement hole and seals the engagement holeairtight.
 12. The disk device of claim 7, wherein the cushioning memberis formed of a fluorine rubber.
 13. The disk device of claim 12, whereinthe second contact surface is subjected to a non-adhesive surfacetreatment and the second surface adhesive force is less than or equal to1/20 the first surface adhesive force.